The present invention relates to an air bag apparatus, and more particularly, to an air bag apparatus suitable for a passenger seat air bag apparatus installed in an instrument panel in front of a passenger seat in a vehicle, such automobile.
A passenger seat air bag apparatus includes a container arranged in an instrument panel in front of a passenger seat, a gas generator, an air bag accommodated in the container and having an opening through which gas ejected from the gas generator is received, and a lid for covering the container. An end portion around the opening is connected to the container. In collision of the vehicle, the gas generator is activated to start inflation of the air bag. When the air bag starts to inflate, the lid is pushed by the air bag and opened, and the air bag inflates into the passenger compartment.
The air bag has a gas inlet through which gas is received from the gas generator. The end portion of the gas inlet is connected to the container.
To fold the air bag, as described in Japanese Unexamined Patent Publication (KOKAI) No. 4-100754, a left side and a right side of the air bag are folded at a middle portion to form an intermediate folded body. The intermediate folded body is then folded in a form of bellows to form a block-like body. The block-like body is accommodated in the container.
A procedure for folding an air bag described in Japanese Unexamined Patent Publication No. 4-100754 will now be described with reference to FIGS. 6 to 12.
FIG. 6 is a perspective view showing an air bag 1, which is spread in a plane, and a sub-container 2. The air bag 1 is an inflatable bag having short sides 1b, which are straight, and left and right long sides 1a, which are curved in an arcuate manner. At the side opposite to the side that faces the passenger, the air bag 1 has at the middle thereof a gas inlet 3 through which gas is received from an inflator, and gas outlets (vent holes) 4 to absorb the impact when a human body hits the deployed (fully inflated) air bag. Reference numerals 5 denote rivet holes. Apertures 6 are formed at the bottom of the sub-container 2 to allow the gas from the inflator to pass therethrough.
As shown in FIG. 7, the air bag 1 is spread out with the sub-container 2 connected thereto. As shown in FIG. 8 and FIG. 9 (cross-sectional view taken along line 9xe2x80x949 in FIG. 8), the portions of the long sides 1a are folded inwardly to form an intermediate folding body, so that the width of the air bag 1 is slightly narrower than the width of the sub-container 2.
Then, as shown in FIG. 10 (side view of FIG. 8 in the direction of line 10xe2x80x9410), the air bag 1 is folded for a number of times in a form of bellows in a direction perpendicular to the straight long sides 1axe2x80x2 of the intermediate folding body. As shown in FIG. 11, the folded portions are overlapped and then accommodated in the sub-container 2 (FIG. 12).
In Japanese Unexamined Patent Publication No. 4-100754, the air bag is folded and accommodated in the sub-container, and the sub-container 2 is accommodated in a main container (not shown). However, the sub-container may be eliminated, and the folded air bag may be directly accommodated in a container (Japanese Unexamined Patent Publication (KOKAI) No. 10-152008).
FIGS. 13 and 14(a) are plan views showing how an air bag is folded in Japanese Unexamined Patent Publication No. 10-152008. An air bag 1xe2x80x2, which has a gas inlet 3xe2x80x2, includes a left side portion and a right side portion, which are folded twice as shown in FIGS. 14(a) and 14(b) to form an elongated intermediate folding body. Then, an upper half of FIG. 14(a) is folded in a form of a roll, and the lower half is folded in a form of bellows and accommodated in a container.
When the air bags 1, 1xe2x80x2 are about to be inflated or deployed by gas from the inflator, the air bags 1, 1xe2x80x2 start to inflate by projecting in a direction perpendicular to the lid. The lid is flush with the surface of the instrument panel. Thus, the air bags 1, 1xe2x80x2 start to inflate in a direction perpendicular to the surface of the instrument panel.
When the air bag starts to inflate in the direction perpendicular to the surface of the instrument panel, the left side portion and the right side portion are folded and overlapped with each other in a complicated manner in the conventional passenger seat air bag apparatus. The air bag, in which the left side portion and right side portion are folded and piled, is inflated so as to push out a forefront portion of the air bag. Thus, in order to sufficiently inflate the air bag, the air bag must be supplied with high pressure gas to apply a pushing force to the forefront portion of the air bag, and the gas generator having a large output must be used.
Accordingly, an object of the present invention is to provide an air bag apparatus that sufficiently and quickly inflates an air bag without increasing the output of the gas generator.
An air bag according to the present invention includes a container having a front opening, a gas generator inflating an air bag, and an air bag accommodated in the container in a folded state and having a gas inlet through which gas is received. The gas inlet has an end portion connected to the container. A lid covers the opening of the container. The air bag has a left side portion and a right side portion folded at a middle portion to form an intermediate folding body having a narrow lateral width, the intermediate folding body being folded along a laterally extending crease line. In the air bag apparatus, the left side portion and the right side portion of the air bag are folded in a form of bellows.
In collision of a vehicle, in which the air bag apparatus is installed, the gas generator is activated, so that the air bag pushes and opens the lid from the inner side, and starts to inflate toward the passenger compartment.
In this case, during inflation, a forefront portion of the air bag is forced out above the instrument panel thereby pulling the left side portion and the right side portion. Since the left side portion and the right side portion are folded in bellows, the left side portion and the right side portion are spread out smoothly when they are pulled by the forefront portion of the air bag.
In the present invention, it is preferred that a clearance of 50 mm or less be provided between the left side portion and the right side portion of the air bag when the left side portion and the right side portion are folded at the middle portion in a form of bellows.
In this specification, the left and right of the air bag refer to the left and right of a passenger sitting in a seat and viewing an air bag apparatus, which is installed in a vehicle.